Relationship between Toxic Metals Exposure via Cigarette Smoking and Rheumatoid Arthritis

Background: The incidence of Rheumatoid Arthritis (RA) has increased among people who smoke tobacco. In the present study, the association between toxic metals exposure via cigarette smoking and rheumatoid arthritis incidence in the population living in Dublin, Ireland, is investigated. The different brands of cigarettes (filler tobacco, filter and ash) consumed by the population studied were analysed for Cd, Ni, and Pb. Methods: The concentrations of toxic elements in biological samples and different components of cigarettes were measured by inductively coupled plasma atomic emission spectrophotometer after microwave-assisted acid digestion. The validity and accuracy of the methodology were checked using certified reference materials. Results: The filler tobacco of different branded cigarettes contain Cd, Ni, and Pb concentrations in the ranges of 1.73 - 2.02, 0.715 - 1.52, and 0.378 - 1.16 mu g/cigarette, respectively. The results of this study showed that the mean values of cadmium nickel, and lead were significantly higher in scalp hair and blood samples of rheumatoid arthritis patients when related to healthy controls, while the difference was significant in the case of smoker patients (p < 0.001). The levels of all three toxic metals were 2- to 3-fold higher in scalp hair and blood samples of non arthritis smoker subjects as compared to nonsmoker controls. Conclusions: The high exposure of toxic metals as a result of cigarette smoking may be synergistic with risk factors associated with rheumatoid arthritis.